Virtual segmentation system and method of operation thereof

ABSTRACT

A virtual segmentation system for use with a routing switch processor and a method of operating the same. In one embodiment, the virtual segmentation system includes a protocol data unit receiver subsystem configured to receive at least a portion of a protocol data unit and assemble the protocol data unit. The virtual segmentation system further includes a virtual segmentation subsystem that is associated with the protocol data unit receiver subsystem and is configured to perform virtual segmentation on the protocol data unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

Application No. Title Inventor Date 09/798,472 A Virtual ReassemblyBennett, Filed Mar. 2, 2001 System And Method of et al. OperationThereof

The above-listed application is commonly assigned and co-pending withthe present invention and is incorporated herein by reference as ifreproduced herein in their entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention is directed, in general, to a communicationssystem and, more specifically, to a virtual segmentation system andmethod of operating the same.

BACKGROUND OF THE INVENTION

Communications networks are currently undergoing a revolution broughtabout by the increasing demand for real-time information being deliveredto a diversity of locations. Many situations require the ability totransfer large amounts of data across geographical boundaries withincreasing speed and accuracy. However, with the increasing size andcomplexity of the data that is currently being transferred, maintainingthe speed and accuracy is becoming increasingly difficult.

Early communications networks resembled a hierarchical star topology.All access from remote sites was channeled back to a central locationwhere a mainframe computer resided. Thus, each transfer of data from oneremote site to another, or from one remote site to the central location,had to be processed by the central location. This architecture is veryprocessor-intensive and incurs higher bandwidth utilization for eachtransfer. This was not a major problem in the mid to late 1980s wherefewer remote sites were coupled to the central location. Additionally,many of the remote sites were located in close proximity to the centrallocation. Currently, hundreds of thousands of remote sites arepositioned in various locations across assorted continents. Legacynetworks of the past are currently unable to provide the data transferspeed and accuracy demanded in the marketplace of today.

In response to this exploding demand, data transfer through networksemploying distributed processing has allowed larger packets ofinformation to be accurately and quickly distributed across multiplegeographic boundaries. Today, many communication sites have theintelligence and capability to communicate with many other sites,regardless of their location. This is typically accomplished on a peerlevel, rather than through a centralized topology, although a hostcomputer at the central site can be appraised of what transactions takeplace and can maintain a database from which management reports aregenerated and operation issues addressed.

Distributed processing currently allows the centralized site to berelieved of many of the processor-intensive data transfer requirementsof the past. This is typically accomplished using a data network, whichincludes a collection of routers. The routers allow intelligent passingof information and data files between remote sites. However, increaseddemand and the sophistication required to route current information anddata files quickly challenged the capabilities of existing routers.Also, the size of the data being transmitted is dramatically increasing.Some efficiencies are obtained by splitting longer data files into acollection of smaller, somewhat standardized cells for transmission orrouting. However, these efficiencies are somewhat offset by theprocessing required to route and split data files (segmentation) orprocess the cells at nodes within the network.

More specifically, the physical segmentation of data files processrequires the system to physically reassemble an entire protocol dataunit (data file) encapsulated in the cells before routing andsegmentation can be performed on the protocol data unit. This physicalreassembly process increases the processing time and therefore decreasesthe throughput of the router. In view of the ever increasing demand forhigher transmission speeds this is highly undesirable.

Accordingly, what is needed in the art is a system to overcome thedeficiencies of the prior art.

SUMMARY OF THE INVENTION

To address the above-discussed deficiencies of the prior art, thepresent invention provides a virtual segmentation system and a method ofoperating the same. In one embodiment, the virtual segmentation systemincludes: (1) a protocol data unit receiver subsystem configured toreceive at least a portion of a protocol data unit and assemble theprotocol data unit, and (2) a virtual segmentation subsystem, associatedwith the protocol data unit receiver subsystem, configured to performvirtual segmentation on the protocol data unit.

In another embodiment, the present invention provides a method ofoperating a virtual segmentation system that includes: (1) receiving atleast a portion of a protocol data unit, (2) assembling said protocoldata unit and (3) performing virtual segmentation on said protocol dataunit.

In another embodiment, the present invention provides router thatincludes a physical interface coupled to a first network, a fabricinterface controller coupled to a fabric network, a fast patternprocessor and a routing switch processor. The fast pattern processorreceives packets of a protocol data unit from the first interfacesubsystem, performs pattern recognition and classification on thepackets and the protocol data unit. The routing switch processorreceives the protocol data unit from the fast pattern processor andtransmits via the second interface subsystem. The routing switchprocessor also includes a virtual segmentation system having: (1) aprotocol data unit receiver subsystem that receives at least a portionof the protocol data unit and assembles the protocol data unit, and (2)a virtual segmentation subsystem that is associated with the protocoldata unit receiver subsystem and performs virtual segmentation on theprotocol data unit.

The foregoing has outlined, rather broadly, preferred and alternativefeatures of the present invention so that those skilled in the art maybetter understand the detailed description of the invention thatfollows. Additional features of the invention will be describedhereinafter that form the subject of the claims of the invention. Thoseskilled in the art should appreciate that they can readily use thedisclosed conception and specific embodiment as a basis for designing ormodifying other structures for carrying out the same purposes of thepresent invention. Those skilled in the art should also realize thatsuch equivalent constructions do not depart from the spirit and scope ofthe invention in its broadest form.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference isnow made to the following descriptions taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a block diagram of an embodiment of a communicationsnetwork constructed in accordance with the principles of the presentinvention;

FIG. 2 illustrates a block diagram of an embodiment of a routerarchitecture constructed in accordance with the principles of thepresent invention;

FIG. 3 illustrates a block diagram of an embodiment of a fast patternprocessor constructed in accordance with the principles of the presentinvention;

FIG. 4 illustrates a block diagram of an embodiment of a routing switchprocessor, which may employ the virtual segmentation system, constructedin accordance with the principles of the present invention; and

FIG. 5 illustrates a flow diagram of an embodiment of a method ofoperating a virtual segmentation system constructed in accordance withthe principles of the present invention.

DETAILED DESCRIPTION

Referring initially to FIG. 1, illustrated is a block diagram of anembodiment of a communications network, generally designated 100,constructed in accordance with the principles of the present invention.The communications network 100 is generally designed to transmitinformation in the form of a data packet from one point in the networkto another point in the network.

As illustrated, the communications network 100 includes a packet network110, a public switched telephone network (PSTN) 115, a source device 120and a destination device 130. In the illustrative embodiment shown inFIG. 1, the packet network 110 comprises an Asynchronous Transfer Mode(ATM) network. However, one skilled in the art readily understands thatthe present invention may use any type of packet network. The packetnetwork 110 includes routers 140, 145, 150, 160, 165, 170 and a gateway155. One skilled in the pertinent art understands that the packetnetwork 110 may include any number of routers and gateways.

The source device 120 may generate a data packet to be sent to thedestination device 130 through the packet network 110. In theillustrated example, the source device 120 initially sends the datapacket to the first router 140. The first router 140 then determinesfrom the data packet which router to send the data packet to based uponrouting information and network loading. Some information in determiningthe selection of a next router may include the size of the data packet,loading of the communications link to a router and the destination. Inthis example, the first router 140 may send the data packet to thesecond router 145 or fourth router 160.

The data packet traverses from router to router within the packetnetwork 110 until it reaches the gateway 155. In one particular example,the data packet may traverse along a path that includes the first router140, the fourth router 160, the fifth router 165, the sixth router 170,the third router 150 and finally to the gateway 155. The gateway 155converts the data packet from the protocol associated with the packetnetwork 110 to a different protocol compatible with the PSTN 115. Thegateway 155 then transmits the data packet to the destination device 130via the PSTN 115. However, in another example, the data packet maytraverse along a different path such as the first router 140, the secondrouter 145, the third router 150 and finally to the gateway 155. It isgenerally desired when choosing a subsequent router, the path the datapacket traverses should result in the fastest throughput for the datapacket. It should be noted, however, that this path does not alwaysinclude the least number of routers.

Turning now to FIG. 2, illustrated is a block diagram of an embodimentof a router architecture, generally designated 200, constructed inaccordance with the principles of the present invention. The routerarchitecture 200, in one embodiment, may be employed in any of therouters illustrated in FIG. 1. The router architecture 200 provides aunique hardware and software combination that delivers high-speedprocessing for multiple communication protocols with fullprogrammability. The unique combination provides the programmability oftraditional reduced instruction set computing (RISC) processors with thespeed that, until now, only application-specific integrated circuit(ASIC) processors could deliver.

In the embodiment shown in FIG. 2, the router architecture 200 includesa physical interface 210, a fast pattern processor (FPP) 220, a routingswitch processor (RSP) 230, and a system interface processor (SIP) 240.The router architecture 200 may also include a fabric interfacecontroller 250 which is coupled to the RSP 230 and a fabric network 260.It should be noted that other components not shown may be includedwithin the router architecture 200 without departing from the scope ofthe present invention.

The physical interface 210 provides coupling to an external network. Inan exemplary embodiment, the physical interface 210 is a POS-PHY/UTOPIAlevel 3 interface. The FPP 220, in one embodiment, may be coupled to thephysical interface 210 and receives a data stream that includes protocoldata units from the physical interface 210. The FPP 220 analyzes andclassifies the Protocol data units and subsequently concludes processingby outputting packets to the RSP 230.

The FPP 220, in conjunction with a powerful high-level functionalprogramming language (FPL), is capable of implementing complex patternor signature recognition and operates on the processing blockscontaining those signatures. The FPP 220 has the ability to performpattern analysis on every byte of the payload plus headers of a datastream. The pattern analysis conclusions may then be made available to asystem logic or to the RSP 230, allowing processing block manipulationand queuing functions. The FPP 220 and RSP 230 provide a solution forswitching and routing. The FPP 220 further provides glueless interfacesto the RSP 230 and the SIP 240 to provide a complete solution forwire-speed processing in next-generation, terabit switches and routers.

As illustrated in FIG. 2, the FPP 220 employs a first communication link270 to receive the data stream from the physical interface 210. Thefirst communication link 270 may be an industry-standard UTOPIA Level3/UTOPIA Level 2/POS—PHY Level 3 interface. Additionally, the FPP 220employs a second communication link 272 to transmit packet andconclusions to the RSP 230. The second communication link 272 may be aPOS—PHY Level 3 interface.

The FPP 220 also includes a management path interface (MPI) 275, afunction bus interface (FBI) 280 and a configuration bus interface (CBI)285. The MPI 275 enables the FPP 220 to receive management frames from alocal microprocessor. In an exemplary embodiment, this may be handledthrough the SIP 240. The FBI 280 connects the FPP 220 and the SIP 240,or custom logic in certain situations, for external processing offunction calls. The CBI 285 connects the FPP 220 and other devices(e.g., physical interface 210 and RSP 230) to the SIP 240. Otherinterfaces (not shown), such as memory interfaces, are also well withinthe scope of the present invention.

The FPP 220 provides an additional benefit in that it is programmable toprovide flexibility in optimizing performance for a wide variety ofapplications and protocols. Because the FPP is a programmable processorrather than a fixed-function ASIC, it can handle new protocols orapplications as they are developed as well as new network functions asrequired. The FPP 220 may also accommodate a variety of searchalgorithms. These search algorithms may be applied to large listsbeneficially.

The RSP 230 is also programmable and works in concert with the FPP 220to process the protocol data units classified by the FPP 220. The RSP230 uses the classification information received from the FPP 220 todetermine the starting offset and the length of the Protocol data unitpayload, which provides the classification conclusion for the Protocoldata unit. The classification information may be used to determine theport and the associated RSP 230 selected for the Protocol data unit. TheRSP 230 may also receive additional Protocol data unit informationpassed in the form of flags for further processing.

The RSP 230 also provides programmable traffic management includingpolicies such as random early discard (RED), weighted random earlydiscard (WRED), early packet discard (EPD) and partial packet discard(PPD). The RSP 230 may also provide programmable traffic shaping,including programmable per queue quality of service (QoS) and class ofservice (CoS) parameters. The QoS parameters include constant bit rate(CBR), unspecified bit rate (UBR), and variable bitrate (VBR).Correspondingly, CoS parameters include fixed priority, round robin,weighted round robin (WRR), weighted fair queuing (WFQ) and guaranteedframe rate (GFR).

Alternatively, the RSP 230 may provide programmable packetmodifications, including adding or stripping headers and trailers,rewriting or modifying contents, adding tags and updating checksums andCRCs. The RSP 230 may be programmed using a scripting language withsemantics similar to the C language. Such script languages are wellknown in the art. Also connected to the RSP 230 are the fabric interfacecontroller 250 and the fabric network 260. The fabric interfacecontroller 250 provide the physical interface to the fabric network 260,which is typically a communications network.

The SIP 240 allows centralized initialization and configuration of theFPP 220, the RSP 230 and the physical interfaces 210, 250. The SIP 240,in one embodiment, may provide policing, manage state information andprovide a peripheral component interconnect (PCI) connection to a hostcomputer. The SIP 240 may be a PayloadPlus™ Agere System Interfacecommercially available from Agere Systems, Inc.

Turning now to FIG. 3, illustrated is a block diagram of an embodimentof a fast pattern processor (FPP), generally designated 300, constructedin accordance with the principles of the present invention. The FPP 300includes an input framer 302 that receives protocol data units viaexternal input data streams 330, 332. The input framer 302 framespackets containing the Protocol data units into 64-byte processingblocks and stores the processing blocks into an external data buffer340. The input data streams 330, 332 may be 32-bit UTOPIA/POS—PHY fromPHY and 8-bit POS—PHY management path interface from SIP 240 (FIG. 2),respectively.

Typically, a data buffer controller 304 is employed to store theprocessing blocks to the external data buffer 340. The data buffercontroller 304 also stores the processing blocks and associatedconfiguration information into a portion of a context memory subsystem308 associated with a context, which is a processing thread. Asillustrated, the context memory subsystem 308 is coupled to a databuffer controller 304.

Additionally, the context memory subsystem 308 is coupled to achecksum/cyclical redundancy check (CRC) engine 314 and a patternprocessing engine 312. The checksum/CRC engine 314 performs checksum orCRC functions on processing block and on the Protocol data unitsembodied with the processing block. The pattern processing engine 312performs pattern matching to determine how Protocol data units areclassified and processed. The pattern processing engine 312 is coupledto a program memory 350.

The FPP 300 further includes a queue engine 316 and an arithmetic logicunit (ALU) 318. The queue engine 316 manages replay contexts for the FPP300, provides addresses for block buffers and maintains information onblocks, Protocol data units, and connection queues. The queue engine 316is coupled to an external control memory 360 and the internal functionbus 310. The ALU 318 is coupled to the internal function bus 310 and iscapable of performing associated computational functions.

Also coupled to the internal function bus 310 is a functional businterface 322. The functional bus interface 322 passes externalfunctional programming language function calls to external logic througha data port 336. In one exemplary embodiment, the data port 336 is a32-bit connection to the SIP 240 (FIG. 2). The FPP 300 also includes aconfiguration bus interface 320 for processing configuration requestsfrom externally coupled processors. As illustrated, the configurationbus interface 320 may be coupled to a data port 334, such as an 8-bitCBI source.

Additionally, coupled to the internal function bus 310 is an outputinterface 306. The output interface 306 sends Protocol data units andtheir classification conclusions to the downstream logic. The outputinterface 306 may retrieve the processing blocks stored in the databuffer 340 and send the Protocol data units embodied within theprocessing blocks to an external unit through an output data port 338.The output data port 338, in an exemplary embodiment, is a 32-bitPOS—PHY connected to the RSP 230 (FIG. 2).

Turning now to FIG. 4, illustrated is a block diagram of an embodimentof a routing switch processor, generally designated 400, that employs avirtual segmentation system and is constructed in accordance with theprinciples of the present invention. The present invention provides avirtual segmentation system that advantageously allows a protocol dataunit to be stored in non-contiguous blocks of memory and then performsegmentation on the protocol data unit without recreating (physicallyreassembling) the entire protocol data unit in a contiguous portion ofmemory. For purposes of the present invention, a “protocol data unit” isthe underlying message in a specific protocol that may be transmittedvia packets over a network. For example, a protocol data unit may be anInternet Protocol (“IP”) message that is transmitted over anAsynchronous Transfer Mode (“ATM”) network. In an ATM network, the IPmessage is broken into ATM cells (packets) before transmission over theATM network. Of course, however, a protocol data unit may be anyprotocol message transmitted over a network and a packet may be aportion of the protocol data unit or the entire protocol data unit.

The routing switch processor 400 is configured to receive a protocoldata unit from an input processor (not shown), such as the fast patternprocessor 220 of FIG. 2. The routing switch processor 400 also transmitsat least a portion of the protocol data unit to a network via a networkinterface (not shown), such as the fabric interface controller 250 ofFIG. 2. For the purposes of the present invention, the phrase“configured to” means that the device, the system or the subsystemincludes the necessary software, hardware, firmware or a combinationthereof to accomplish the stated task.

In the illustrated embodiment, the routing switch processor 400 includesan input interface 410, a protocol data unit receiver subsystem 420, amemory 430, a virtual segmentation subsystem 440 and an output interface450. The input interface 410 receives the protocol data units to beprocessed. In one embodiment, the input interface 410 receives theprotocol data units from an input processor, such as the fast patternprocessor 420. The input interface 410 may also receive classificationinformation or routing information associated with each protocol dataunit. In another embodiment, the input interface 410 may also sendrouting information or transmit commands to the protocol data unitreceiver subsystem 420.

The protocol data unit receiver subsystem 420 is configured to receiveat least a portion of a protocol data unit and assemble the protocoldata unit. The protocol data unit receiver subsystem 420 also stores theprotocol data unit in blocks in the memory 430. In one embodiment, theprotocol data unit receiver subsystem 420 is further configured toprocess a plurality of interleaved portions of different protocol dataunits.

In the illustrated embodiment, the protocol data unit receiver subsystem420 includes an assembler subsystem 422 and a transmit queue subsystem424. The assembler subsystem 422 is configured to receive at least aportion of the protocol data unit from the input interface 410. Theassembler subsystem 422 also assembles each protocol data unit andstores the assembled protocol data unit in at least one block in thememory 430. In one embodiment, the assembler subsystem 422 may requestthe transmit queue subsystem 424 to allocate space in the memory 430 foreach protocol data unit.

The transmit queue subsystem 424 is configured to maintain a linked listof each block associated with each of the protocol data units. Inanother embodiment, the transmit queue subsystem 424 may maintain alinked list for each block of a protocol data unit stored in the memory430. The transmit queue subsystem 424 is also configured to perform arouter function on the protocol data unit contained within the blocksand maintain at least one queue for transmission of the protocol dataunit. In one embodiment, the assembler subsystem 422 and the transmitqueue subsystem 424 are further configured to process a plurality ofinterleaved portions of different protocol data units.

The virtual segmentation subsystem 440 is associated with the protocoldata unit receiver subsystem 420 and is configured to perform virtualsegmentation on the protocol data unit. For example, the protocol dataunit receiver subsystem 420 stores portions of the protocol data unit inblocks as it is received. The blocks associated with the protocol dataunit may not be stored in contiguous locations and may have multipleblocks from different protocol data units interleaved between them.Instead of retrieving and physically reassembling the entire protocoldata unit before segmenting the protocol data unit, the virtualsegmentation subsystem 440 advantageously performs the segmentation oneach block as it is retrieved. The segmentation may include convertingthe block to the appropriate transmission protocol and append headerinformation. For example, if the protocol data unit is an IP message,the virtual segmentation subsystem 440 retrieves each block of the IPmessage, stores a portion of the IP message in an ATM cell, adds an ATMcell header and transmits the ATM cell. Of course, however, the presentinvention is not limited to the type of segmentation described above. Inother embodiments, the present invention may perform additional or othersteps than described above. Additionally, the virtual segmentationsubsystem may be further configured to process a plurality ofinterleaved portions of different protocol data units.

In the illustrated embodiment, the virtual segmentation subsystem 440may also include a stream editor subsystem 442 configured to performvirtual segmentation. The stream editor subsystem 442, in oneembodiment, is also configured to perform packet modification on theprotocol data units as they are being sent to the output interface 450for transmission. The modifications may include modifying the protocoldata unit to implement IP and upper layer protocols, encapsulating theprotocol data unit into AAL5 protocol data units and converting orsegmenting the protocol data unit into ATM cells with the appropriateheader information.

Additionally, the stream editor subsystem 442 may be configured toconvert between a first protocol and a second protocol. In anotherembodiment, the stream editor subsystem 442 may be further configured togenerate a validity check on the protocol data unit or on at least aportion of the protocol data unit. The validity checks may be a cyclicredundancy check (CRC), a CRC for asynchronous transfer mode (ATM)adaptive layer 5 (AAL5) over ATM, and a CRC-10 for operation,administration, maintenance (OAM) cells. Of course, however, the presentinvention is not limited to the validity checks or functions listedabove. In other embodiments, the stream editor subsystem 442 may performany type of validity check, any type of function or any type ofmodification associated with the transmission of protocol data units.

The output interface 450 receives the virtually segmented protocol dataunits from the virtual segmentation subsystem 440 and transmits at leasta portion of the protocol data unit to a network via a network interface(not shown), such as the fabric interface controller 250 of FIG. 2. Inanother embodiment, the output interface 450 may be coupled to aplurality of network interfaces that allow the protocol data units to berouted to different networks or communication links associated with eachnetwork interface.

One skilled in the art should know that the present invention is notlimited to a virtual segmentation system within a routing switchprocessor. Nor is the present invention limited to the types ofprocessing described above. In other embodiments, the virtualsegmentation system may be employed in other devices that processprotocol data units.

Turning now to FIG. 5, illustrated is a flow diagram of an embodiment ofa method, generally designated 500, of operating a virtual segmentationsystem constructed in accordance with the principles of the presentinvention. In FIG. 5, the virtual segmentation system first performsinitialization in a step 502.

After initialization, the virtual segmentation system determines ifthere are any protocol data units to process in a decisional step 504.If there is a protocol data unit to process, the virtual segmentationsystem receives at least a portion of the protocol data unit andassembles the protocol data unit in a step 510. Next, the virtualsegmentation system stores the protocol data unit or at least theportion of the protocol data unit in blocks in memory in a step 512. Thevirtual segmentation system may then maintain a linked list associatedwith the protocol data unit in a step 514. In one embodiment, thevirtual segmentation system maintains a linked list of each of theblocks associated with the protocol data unit.

The virtual segmentation system then determines if the portion receivedis the end of the protocol data unit in a decisional step 520. If it isnot the end of the protocol data unit, the virtual segmentation systemthen returns to receive and process another portion of the protocol dataunit in the step 510. If it is the end of the protocol data unit, thevirtual segmentation system then performs a function on the protocoldata unit in a step 530. In one embodiment, the virtual segmentationsystem may perform router related functions on the protocol data unit,such as quality of service checks and validity checks. In anotherembodiment, the virtual segmentation system may perform a function onselected protocol data units or the virtual segmentation system may notperform any function. Next, the virtual segmentation system maintains aqueue structure for the protocol data unit for transmission in a step532. The virtual segmentation system then returns to process the nextprotocol data unit in the decisional step 504.

If the virtual segmentation system did not have any protocol data unitsto process in the decisional step 504, the virtual segmentation systemthen determines if there is a queued protocol data unit to transmit in adecisional step 540. If there are no queued protocol data units totransmit, the virtual segmentation system then returns to process thenext protocol data unit in the decisional step 504.

If there is a queued protocol data unit to transmit, the virtualsegmentation system performs virtual segmentation on the protocol dataunit in a step 550. Virtual segmentation is discussed in more detail inFIG. 4. In one embodiment, the virtual segmentation may includeconverting between a first protocol and a second protocol. Next, thevirtual segmentation system may then generate validity checks in a step552. In one embodiment, the validity checks may be a CRC, a CRC for AAL5over ATM and a CRC-10 for OAM cells. In another embodiment, the validitychecks may be generated as part of the virtual segmentation process anda validity check is generated for each generated segment.

Next, the virtual segmentation system may transmit the virtuallysegmented protocol data unit in a step 554. In one embodiment, thevirtual segmentation system may transmit each segmented portion of theprotocol data unit as it is being virtually segmented. In anotherembodiment, the virtual segmentation system may transmit or route thevirtually segmented protocol data unit to different network interfacecontrollers depending upon routing information associated with theprotocol data unit. The virtual segmentation system then returns toprocess the next protocol data unit in the decisional step 504.

One skilled in the art should know that the present invention is notlimited to receiving protocol data units and then performing virtualsegmentation. The present invention may receive and process one protocoldata unit and at the same time perform virtual segmentation on adifferent protocol data unit. Also, other embodiments of the presentinvention may have additional or fewer steps than described above.

Although the present invention has been described in detail, thoseskilled in the art should understand that they can make various changes,substitutions and alterations herein without departing from the spiritand scope of the invention in its broadest form.

1. A router, comprising: a physical interface coupled to a firstnetwork; a fabric interface controller coupled to a fabric network; afast pattern processor that receives packets of a protocol data unitfrom said physical interface, performs pattern recognition andclassification on said packets and said protocol data unit; and arouting switch processor that receives said protocol data unit from saidfast pattern processor and transmits via said fabric interfacecontroller, said routing switch processor having a virtual segmentationsystem, including: a protocol data unit receiver subsystem that receivesat least a portion of said protocol data unit and assembles saidprotocol data unit; and a virtual segmentation subsystem, associatedwith said protocol data unit receiver subsystem, that performs virtualsegmentation on said protocol data unit.
 2. The router as recited inclaim 1 wherein said protocol data unit receiver subsystem furtherincludes: an assembler subsystem that receives said at least a portionof said protocol data unit and assembles said protocol data unit; and atransmit queue subsystem that maintains a linked list associated withsaid protocol data unit, performs a function on said protocol data unitand maintains at least one queue structure for transmission.
 3. Therouter as recited in claim 2 wherein said assembler subsystem furtherstores said at least a portion of said protocol data unit in at leastone block and said transmit queue subsystem further maintains a linkedlist of said at least one block.
 4. The router as recited in claim 1wherein said virtual segmentation subsystem further includes a streameditor subsystem that performs said virtual segmentation.
 5. The routersystem as recited in claim 4 wherein said stream editor subsystem herconverts between a first protocol and a second protocol.
 6. The routeras recited in claim 4 wherein said stream editor subsystem furthergenerates a validity check selected from the group consisting of: acyclic redundancy check (CRC), a CRC for asynchronous transfer mode(ATM) adaptive layer 5 (AAL5) over ATM, and a CRC-10 for operation,administration, maintenance (OAM) cells.
 7. The router as recited inclaim 1 wherein said protocol data unit receiver subsystem and saidvirtual segmentation subsystem further process a plurality ofinterleaved portions of different protocol data units.